board is gigabyte 5ax, and cpu is k6-2+
today i just wanted to see how it performs at low clock. knowing minimum multiplier that k6-2+ accept is 2.5, i set fsb and ratio jumpers to 66 and 2.5x, and you expect a clock of 166mhz right? but things went out of my expectation:

at powerup it displays 138mhz, and i dunno how its calculated.
cpu-z and everest reports 53.3*2.5=133
wcpuid and sisoft reports 66*2=133

by comparing several benchmark results with reference, i can confirm that cpu is indeed running at 133mhz rather than expected 166mhz. and i don't think this board's fsb is software-changable, so 66*2 should be the correct report. but what has made the k6-2+'s multiplier slipped from jumpered 2.5x to 2x?
those who have 5ax or other socket7 boards and k6-2+/k6-3+ can also have a shot at this.